Ralink RT2600 problem with CentOs 4.4

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Hi, This is my first-time using linux and I'm very newbie. Here is my problem:

I'm using Ralink chipset wireless card (RT2600) with CentOs 4.4. I configure the card is fine but I have two problems.

1. My wireless interface(ra0) isn't start when I reboot the PC. I manually start it by "ifconfig ra0 up".
2. I can't get IP address automatically from Router DHCP. I manually get IP using "dhclient".

The following my interface configuration(ifcfg-ra0):

DEVICE=ra0
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Wireless
MODE=Managed
ESSID=my router SSID

Can anyone please help me -
How to auto start the interface when I reboot the PC?
How to automatic get IP when I start the interface?

Thanks,

Ksein